This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. Primary support for the subproject and the subproject's principal investigator may have been provided by other sources, including other NIH sources. The Total Cost listed for the subproject likely represents the estimated amount of Center infrastructure utilized by the subproject, not direct funding provided by the NCRR grant to the subproject or subproject staff. We propose a systematic multi-edge XANES study to determine spectroscopic signatures for Ru-based anticancer metallodrugs that correlate with in vitro activity. This would make possible the prediction of biological function from chemical structure and thus aid the drug design and optimization process. Spectral information collected at the ligand (S and Cl) K- and metal (Ru) L-edges will provide insights into the electronic structure of Ru(II) and Ru(III) complexes. These will be supplemented with EXAFS analysis of metal (Ru) K-edge spectra for structurally ill-defined solution samples. We have synthesized a large library of Ru(III) and Ru(II) complexes with dimethylsulfoxide, chloride, imidazole, and indazole ligands. We have already obtained Cl K-edge and Ru L-edge data for some of the complexes and identified spectral features that could be candidates for signatures of biological activity. We plan to extend these studies to ten members of our Ru complex library in pure solid, hydrolyzed, DNA, and protein bound forms at neutral and acidic (cancerous cells) pH conditions. These in vitro modeling studies have the potential to provide the base of future in vivo studies. Also, the in vitro measurements will be supplemented with electronic structure calculations to aid the spectral assignments and provide rational for the structural information obtained for solution samples.